Blow molded container structure, cap therefore and method of forming said neck

ABSTRACT

The neck of a container has a smooth seal surface engaged by the inner skirt or plug of a cap. Such surface is free of trim and parting line flaws which are characteristic of blow-molded jars because the surface is formed in such a way that the seal surface is not in contact with mold parting lines and further the trim of the neck (excess plastic) is located away from the sealing surface. In one form of the disclosure, above the sealing surface the neck wall slants outward and then bends upward-inward in a short, tapered stretch about 18° to the horizontal which engages the underside of the cap disk to compress against the disk or a liner or foil. In another form of the invention, above the seal surface the neck extends outward and then upward and then inward in a flange which is trimmed along a line which has a circumference no less than the circumference of the seal surface. The exterior of the neck is formed with shoulders which engage over locking beads on the interior of the outer skirt of the cap.

This is a division of application Ser. No. 08/847,928, filed on Apr. 28,1997, U.S. Pat. No. 5,964,362, which was a file wrapper continuation ofSer. No. 08/385,808 filed Feb. 9, 1995, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a new and improved blow molded neckconstruction for bottle or other container, a cap therefor and method offorming said neck. More particularly, it relates to the neck finish fora blow molded plastic bottle characterized by the fact that when usedwith a cap having a plug (i.e., inner skirt) the surface of the neckagainst which the plug seals is a seal surface without parting lines anda portion above the seal surface comprises an inward directed thinflexible flange.

2. Description of Related Art

An exemplar of the prior art is U.S. Pat. No. 4,691,834 which shows anupward inward directed flexible flange sealing against the corner of theintersection of the outer wall of the plug and the underside of the topof the cap. The neck sealing surface is, inherently, somewhat uneven andragged since the neck is cut or sheared adjacent this sealing surface.In the present invention, however, the neck is trimmed at the edge ofthe upper flexible flange but such edge is not the portion of the neckwhich seals against the cap plug.

The references cited against said U.S. Pat. No. 4,691,834 are likewisedistinguishable.

U.S. Pat. Nos. 4,625,876 and 4,798,301 show curved plug contactingsurfaces but these are of substantially the same diameters as the inneredge of the flanges which engage the underside of the top of the cap.

SUMMARY OF THE INVENTION

The bottle of the present invention is blow molded in a split mold bytechniques well known in the art. The surfaces of the mold which definethe neck structure cause the neck shape hereinafter described. An upperportion of the parison above the neck is trimmed or cut from the neckaccording to conventional practice (e.g. pull-up trim, spin trim, etc.)The circle at which the upper portion of the parison is severed from theneck is the inner edge of an inward upward slanted flange. The other endof the flange merges into a curved surface which extends inward agreater distance than the aforesaid edge to merge with an internalsealing surface of lesser diameter than said edge. The neck structureabove the neck sealing surface has rapidly changing diameters which forma flexible membrane due to parison stretching in the blow moldingprocess. Below the sealing surface the exterior of the neck structureslants downward outward to a horizontal shoulder and then extendsdownwardly and then outwardly to a second or lower shoulder.

The cap with which the neck is used has a top having a depending centralplug or inner skirt, the outer surface of which seals tightly againstthe sealing surface of the neck. The cap also has an outer skirt havinginternal sealing beads which engage the upper and lower shoulders of theneck to hold the cap in place. The lower portion of the outer cap skirtmay be removed by the user engaging and pulling a pull tab which causesthe lower part of the skirt to disengage at a circumferential scoreline. Until such lower skirt is removed, the cap and neck aretamper-evident.

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a neck portion of a jar inaccordance with the present invention partially broken away to revealstructure.

FIG. 2 is an enlarged sectional view of the neck structure and a portionof a blow dome superimposed thereabove.

FIG. 3 is a side elevational view of a cap with which the neck is used,the cap being partially broken away in section to reveal internalconstruction.

FIG. 4 is an enlarged sectional view of a portion of FIG. 3.

FIG. 5 is a further enlarged fragmentary bottom plan view of a portionof the cap showing a top view of the pull tab.

FIG. 6 is a fragmentary sectional view taken substantially along theline 6—6 of FIG. 5.

FIG. 7 is an enlarged sectional view showing schematically the seatingof the cap on the neck.

FIG. 8 is a view similar to FIG. 7 of a prior art device.

FIG. 9 is a view similar to FIG. 7 of a modification.

FIG. 10 is a view similar to FIG. 7 of another modification.

FIG. 11 is a view similar to FIG. 7 showing possible distortion of thecap top if pressure is applied to the container.

FIG. 12 is an enlarged view of the neck structure showing an alternateseal area.

FIG. 13 is a view similar to FIGS. 9 and 10 showing modified sealingsurface positions.

FIG. 14 is a vertical sectional view through a modified container neckand portions of the mold and blow pin forming same.

FIG. 15 is a view of similar to FIG. 14, showing the blow pin in raisedposition.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to those embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims.

Neck 11 is formed on a thin-walled jar or other container and has acurved primary seal surface 12 which is very smooth and is distinguishedby the absence of parting lines inasmuch as it is formed by air pressureor other mechanical means during the blow molding process and is notformed by the mold halves and thus does not have a mold parting lineformed therein. As shown in FIG. 12, seal surface 12 may be vertical orit may be curved, as shown in FIG. 2. Further, the primary sealingsurface has minimal ovality, by reason of the way it is formed. Abovesurface 12 the neck structure extends outwardly in a outward stretch 13which terminates in an upward bend 14. Above bend 14 is a thin, taperedupward-inward extending flange 16, the inner edge of which is of greaterdiameter than the diameter of surface 12. Below surface 12 the neckextends downwardly-outwardly in a slanted stretch 17 which terminates ina short vertical stretch 18, there being an inward directedsubstantially horizontal upper shoulder 19 below surface 18. Verticalstretch 21 extends downwardly from the inner edge of shoulder 19terminating in an inwardly curved portion 22 which merges with anoutward downward stretch 23. An approximately vertical short surface 24(of greater diameter than surface 18) terminates in a second or lowerhorizontal inward directed shoulder 26. Vertical stretch 27 depends fromthe inner edge of shoulder 26, merging with an outward stretch 30 whichmerges with an outward downward stretch 29. The lower end of stretch 29merges with an inward downward stretch 31.

In accordance with one form of standard blow molding practice, a parisonof the plastic material from which the container is to be formed isdeposited in the split mold. Air is blown into the parison to expand itto fill the mold. In one form of the present invention, the mold hasinserts which shape the finish of the neck of the container heretoforedescribed and above these neck inserts the mold widens out to establishwhat is known as a blow dome of excess material. The blow dome issevered from the neck finish by well-known means. In accordance with thepresent invention, as distinguished from prior neck finishes, the blowmold is severed at the inner edge of flange 16. Severing the edge of theneck from the blow dome may cause a rough surface. One of the advantagesof the present invention is that the edge at which the blow dome issevered is not the primary sealing surface 12. Thus directing attentionto FIG. 2, blow dome 33 has an outward upward slanted stretch 34 merginginto a curved stretch 36 which has an inward slanted stretch 37. The cutline 38 is a circle wherein the stretch 34 is severed from the inneredge of flange 16. By reason of the almost 180° bend 14, and the rapiddiameter changes within a relatively short vertical distance flange 16is thin and flexible.

Another way to achieve the neck structure of the present invention is toemploy what is commonly referred to as “pull-up” trim. In this case thecut line 38 is achieved by having a close diametrical fitting of a blowpin positioned internally within the parison and sets of shear steelsmounted on the split mold. Diameters of the blow pin are typically 0.001inch to 0.004 inch smaller than that diameter defined by the shearsteels in closed position. After blowing of the neck and container, theportion of the parison above cut line 38 is severed from the neckportion below cut line 38 by upward movement of the blow pin relative tothe shear steels.

It will be understood that the type plastic used to mold neck 11 may beany suitable relatively hard plastic such as polyethylene.

One form of closure or cap used with the present invention is shown inFIGS. 3-7. The closure of FIGS. 3-7 comprises an indented circular top42 having a short peripheral cylindrical upward extending member 43 fromwhich extends outwardly a stack rim 44. The outer edge of rim 44 has adepending downward stretch 46 which merges into vertical, substantiallycylindrical upper outer skirt 48. The lower end of skirt 48 merges intoan outward downward slanted stretch 55. Below stretch 55 is the lowersubstantially cylindrical outer skirt 49. An internal scoreline 51separates stretch 55 from lower skirt 49. Below lower skirt 49 the caphas an outward downward slanted flange 52 which, for practical purposes,rests against the surface 30 of neck 11. Interrupted upper inner beadsections 53 engage under the shoulder 19. Lower inner bead 54 at thelower end of skirt portion 49 engages under the shoulder 26. When thecap is attached, the beads 53 and 54 prevent cap 41 from being removedfrom neck 11. In order to enable the user to grip cap 41, ribs 50 extendoutwardly from member 48 merging with the outer surface of lower skirtportion 49 as best shown in FIG. 7. Ribs 50 also impart columnarstrength to the closure to transfer vertical force and prevent closurecollapse during axial application of the closure to the finish.

At one portion of the circumference of lower skirt 49 (as best shown inFIGS. 5 and 6), spaced downwardly therefrom is a horizontal pull tab 57having a curved connection 58 to skirt 49. The interior of skirt 49 isformed with a notch 59 where tab 57 joins lower skirt 49. Notch 59 formsa vertical line of weakness through skirt 49. Enlargement 61 is formedon the distal edge of pull tab 57. The flange 52 is formed thinner thanthe rest of flange 52 in the thin area 62 adjacent tab 57.

As a downward extension of cylindrical member 43 the cap 41 is formedwith a depending skirt extension 66, the lower inner edge of which isformed with a radius 67. The inner surface of member 43 seals againstprimary seal surface 12. The vertical position of cap top 42 can beadjusted to provide for compression of surface 12 against the adjacentsurface of member 43.

Directing attention to FIG. 7 it will be seen that the surface 12 is theprimary sealing surface against the member 43. As has been noted, thesurface 12 is very smooth and hence forms a very effective seal againstthe member 43.

When the cap is applied, the beads 53 and 54 lock under the shoulders 19and 26 to prevent removal of the cap and hence are tamper evidencing.When the user wishes to open the container, the user grips theenlargement 61 and bends the pull tab 57 outwardly and then pullscircumferentially, tearing the lower skirt 49 from the upper capportion. The user may then grip under the surface 55 which, as shown inFIG. 7, is spaced from the bottle finish by a considerable gap, and pullupwardly causing the interrupted upper bead segments 53 to disengagefrom shoulder 19 so that the cap may be removed. The ribs 50 rigidifythe upper portion of the cap to allow the forces necessary to push thecap onto the bottle from causing the cap to buckle. The portion of thecap above line 51 constitutes a reclosure cap and may be pressed back onthe neck after portions of the contents of the jar are dispensed asfrequently as required.

Comparison of FIG. 7 with prior art structure shown in FIG. 8 shows thatin the present invention the very smooth surface 12 causes a tight sealagainst the exterior of member 43 and the flange 16 need not seal atall, whereas in the prior all the cut inner edge of the flange is aprimary seal. The primary seal surface 12 has minimum deviation fromovality as compared to FIG. 8 where the primary seal is coincident witha trim surface. Bottles of this type of this invention and the prior artwere molded. The ovalty of the two types was measured. The unexpectedresult of these experiments was that the current invention produced asignificantly more circular primary seal area. Refer to Table A. fortabulated results. The stretch occurring on both sides of the primaryseal 12 is primarily contributing to the superior ovality anddifferentiate it from prior art.

TABLE A STD BOTTLE STYLE PRESENT INVENTION Run Run Run Run Run Run RunRun A B C D A B C D 0.055 0.020 0.048 0.028 0.024 0.058 0.002 0.0150.053 0.002 0.056 0.015 0.006 0.010 0.106 0.030 0.062 0.000 0.044 0.0100.017 0.002 0.013 0.010 0.043 0.010 0.058 0.003 0.016 0.004 0.005 0.0270.058 0.029 0.025 0.009 0.014 0.013 0.005 0.034 0.064 0.016 0.055 0.0030.011 0.060 0.017 0.017 0.011 0.005 0.059 0.002 0.004 0.003 0.017 0.0190.013 0.049 0.005 0.007 0.042 0.006 0.045 0.002 0.013 Average 0.028Average 0.016

If the contents of the container are non-viscous (e.g., brine-packedpickles) or if the walls of the container are easily squeezed duringtransportation or handling, top 42 may be subjected to upward pressurecausing it to become “domed” (outwardly convex). Such action may causethe inner skirt member 43 to pivot away from curved primary seal 12,resulting in leakage. This effect is illustrated in FIG. 11.

FIG. 9 shows one remedy for such leakage. Contrasting FIG. 9 with FIG. 7it will be seen that top 42 b is raised relative to stack rim 44 b andthat the contact of surface 12 b with inner skirt member 43 b is moreclosely opposite top 42 b. In addition, reducing the vertical spacingbetween top 42 b and stack rim 44 b reduces the lever arm andcorresponding mechanical advantage of the inward force componentgenerated by internal pressure. Hence doming of top 42 b does not resultin pivoting of skirt 66 b out of sealing contact with surface 12 b. FIG.11 shows how pressure applied to the container (as by squeezing the sidewall) may cause top 42 b to bow upward, pulling plug 66 b away from suchsurface 12 b.

FIG. 10 shows another remedy for leakage due to doming of surface 42 c.A plurality of angularly spaced, substantially radially gussets 71 areformed at the intersection of top 42 c and cylindrical member 43 c.Gussets 71 prevent member 43 c from pivoting away from surface 12 c. Asimilar result can be achieved by replacing gussets 7 with a continuousreinforcing bead or shoulder at the intersection of the exteriorsurfaces of top 42 c and member 43 c.

FIG. 12 illustrates a shape wherein seal surface 12 d is cylindricalrather than curved.

FIG. 13 shows a structure in which top 42 c is closer to the level ofrim 44 e. Surface 12 e engages the surface of cylinder 43 e below thelevel of top 42 e.

Directing attention to the modification shown in FIGS. 14 and 15,formation of a modified container neck is shown. Such a neck mayresemble that shown in U.S. Pat. No. 4,699,287, with an importantmodification, as hereinafter explained. In FIG. 14 the parison formingthe neck is shown between a blow pin 86 and shear steel 76 and neckinsert 21 as molding is being completed.

Shear steel 76 has an inward projector 77 terminating in a verticalinward shearing edge 78. Blow pin 86 has a lower cylindrical portion 87having an outward shearing edge 88 with a groove 89 thereabove.

As shown in FIG. 14, blow molding of the parison to the shape of shearsteels 76 and neck insert 81 has just been completed. Edge 88 is locatedbelow edge 78. Air blowing through hole 91 has formed vertical stretch101 and inward horizontal stretch 102 as well as the portionsthereabove. The smooth, vertical, lower cylindrical portion 87 hasformed internal primary seal surface 12 f.

The blow pin 86 then moves from the position of FIG. 14 to the positionof FIG. 15. The neck structure is sheared between edges 78 and 88. Innerflange edge 96 is formed where the edges 78, 88 have sheared the sameand the parison sheared-off portion 94 thereabove is discarded.

It is noted that edge 96 is of a larger diameter than primary sealsurface 12 f. hence the hollow plug or inner skirt such as that shown inU.S. Pat. No. 4,699,287 seated on the container neck seals againstsurface 12 f instead of surface 96. Since blow pin 86 has no partingline surface 12 f has no flash. Surface 12 f is smooth and its diameteris always the same during repetitive molds and hence makes a superiorseal with the cap plug.

In FIGS. 8, 9, 10, 12, 13 and 14 in general the same reference numeralsare used for parts corresponding to FIG. 7, followed by subscripts a, b,c, d, e and f respectively.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. An intermediate article of manufacture forsubsequent trimming to form a neck portion for a blow-molded plasticcontainer for use with a cap having a top, an outer skirt depending fromthe top and a plug substantially vertical depending from the top, theplug being located inward of the outer skirt with an annular gap betweenthe skirt and the plug, said article of manufacture comprising a smooth,internal, circumferential primary seal surface characterized by theabsence of mold parting lines positioned and dimensioned to sealinglyengage the plug, an outward bend at an upper end of said sealingsurface, an outward extending stretch joined to said outward bend, anupward bend at an outer end of said outward extending stretch, and aninwardly-upwardly extending flange above said upward bend, said flangehaving a terminus having a circumference greater than said sealingsurface, and a blow dome extending upwardly of said terminus, saidterminus comprising a trim line for subsequently trimming off said blowdome.
 2. The intermediate article of manufacturing of claim 1 in whichsaid seal surface is circular in plan view with a minimum variation fromovality.
 3. The intermediate article of manufacturing of claim 1 inwhich said seal surface is curved in vertical cross-section.
 4. Theintermediate article of manufacturing of claim 1 in which said sealsurface is substantially straight in vertical cross-section.
 5. Theintermediate article of manufacturing of claim 1 in which no part ofsaid neck portion above said seal surface is thicker than said sealsurface.
 6. The intermediate article of manufacturing of claim 1 inwhich said outward extending stretch is spaced apart from said flange.7. The intermediate article of manufacturing of claim 1 in which saidflange has a bottom surface spaced from said outward extending stretch.8. The intermediate article of manufacture of claim 1 in which thehorizontal distance between said seal surface and said upward bend isgreater than the minimum vertical distance between said upper end ofsaid seal surface and said terminus.